How severe is CVE-2026-6733?

CVE-2026-6733 has a CVSS 3.x base score of 3.7, rated low severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2026-6733 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (14th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-6733?

CVE-2026-6733 affects Nodejs Undici. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-6733?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-6733 have an EU (EUVD) identifier?

Yes. CVE-2026-6733 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37769.

When was CVE-2026-6733 published?

CVE-2026-6733 was published on 2026-06-17 and last updated on 2026-06-27.

CVE-2026-6733

CVE-2026-6733 is a low-severity vulnerability in Nodejs Undici with a CVSS 3.x base score of 3.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-367.

Key facts

Severity: Low (CVSS 3.x base score 3.7)
EPSS exploit prediction: 0% (14th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-37769
Weakness: CWE-367
Affected product: Nodejs Undici
Published: 2026-06-17
Last modified: 2026-06-27

Description

Impact: Undici's HTTP/1.1 client is vulnerable to response queue poisoning on reused keep-alive sockets. An attacker-controlled upstream server can inject an unsolicited HTTP/1.1 response onto an idle socket after a request completes. When the client dispatches the next request on that socket, it associates the injected response with the new request, causing responses to be delivered to the wrong requests. This requires an attacker-controlled or compromised upstream HTTP/1.1 server and keep-alive connection reuse. Patches: Upgrade to undici v6.26.0, v7.28.0 or v8.5.0. Workarounds: Disable keep-alive connection reuse by setting keepAliveTimeout: 0 on the Client or Pool.

Frequently asked questions

What is CVE-2026-6733?: Impact: Undici's HTTP/1.1 client is vulnerable to response queue poisoning on reused keep-alive sockets. An attacker-controlled upstream server can inject an unsolicited HTTP/1.1 response onto an idle socket after a request completes. When the client dispatches the next request on that socket, it associates the injected response with the new request, causing responses to be delivered to the wrong requests. This requires an attacker-controlled or compromised upstream HTTP/1.1 server and keep-alive connection reuse. Patches: Upgrade to undici v6.26.0, v7.28.0 or v8.5.0. Workarounds: Disable keep-alive connection reuse by setting keepAliveTimeout: 0 on the Client or Pool.
How severe is CVE-2026-6733?: CVE-2026-6733 has a CVSS 3.x base score of 3.7, rated low severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2026-6733 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (14th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-6733?: CVE-2026-6733 affects Nodejs Undici. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-6733?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-6733 have an EU (EUVD) identifier?: Yes. CVE-2026-6733 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37769.
When was CVE-2026-6733 published?: CVE-2026-6733 was published on 2026-06-17 and last updated on 2026-06-27.

References

Affected products (1)

cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*

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